https://nalar.dev/tags/asynchronous-systems/ Recent content in Asynchronous Systems on Nalar Hugo en-us Thu, 10 Sep 2026 00:00:00 +0700 https://nalar.dev/testing-asynchronous-behavior-with-eventual-assertions/ Thu, 10 Sep 2026 00:00:00 +0700 https://nalar.dev/testing-asynchronous-behavior-with-eventual-assertions/ <h1 id="testing-asynchronous-behavior-with-eventual-assertions">Testing Asynchronous Behavior with Eventual Assertions</h1> <p>A test starts background work and then checks the result. On a fast machine the work finishes first and the test passes. Under CI load, the assertion runs a few milliseconds earlier and fails. Someone adds <code>sleep(1 second)</code>. The failure disappears, but every successful run now pays a full second, and a sufficiently slow run can still fail.</p> <p>The problem is not that the test needs a longer delay. The test doesn&rsquo;t know exactly when the result will become observable.</p>